380 Local Delivery of CpG ODN Induces a Mucosal Innate Antiviral State and Prevents Genital HSV-2 Infection A. A. Ashkar, K. L. Rosenthal* McMaster Univ Hlth Sci Ctr, Hamilton, Canada
Background: Mucosal surfaces are the entry site for the vast majority of infectious pathogens and provide the first line of defense against infection. In addition to the epithelial barrier, the innate immune system plays a key role in recognizing and rapidly responding to invading pathogens. Since CpG oligodeoxynucleotides (ODN) potently activates the innate immune system via Toll-like receptor 9 (TLR9), we initially studied whether local mucosal delivery of CpG ODN could protect against intravaginal (IVAG) infection with herpes simplex virus type 2 (HSV-2) and then went on to characterize the mechanism of this protection.
Methods: Various knock-out and normal mouse strains were treated vaginally with CpG ODN, control non-CpG ODN, or left untreated prior to IVAG HSV-2 infection. The effects of CpG on the genital mucosa were studied using histology. Transgenic mice containing the HSV immediate-early gene (ICP4) promoter fused to the betagalactosidase gene and HSV-2 expressing green fluorescent protein were used to study entry and replication of HSV-2 in genital mucosa. Cell lines that naturally express or were transformed with Toll-like receptor 9 (TLR9) were used to determine the role of TLR9 in induction of the antiviral state by CpG ODN.
Results: Local transmucosal, but not systemic, delivery of CpG ODN induced potent protection against IVAG HSV-2 infection. This protection was innate immune-mediated and occurred in the absence of all lymphoid cells and independently of IFNgamma. Local delivery CpG ODN caused rapid proliferation of the genital mucosa and was associated with local inflammatory infiltrates. CpG ODN treatment inhibited HSV-2 replication, but not entry, in vaginal epithelial cells. The antiviral effects of CpG ODN treatment were shown to be mediated through TLR9 signaling.
Conclusions: This is the first report of induction of a novel antiviral state following local mucosal delivery of CpG ODN that protects against intravaginal HSV-2 infection. These results have important implications for prevention of genital HSV-2 in humans and potentially other sexually transmitted infections, including HIV-1.
